diff --git a/studio/backend/core/inference/llama_cpp.py b/studio/backend/core/inference/llama_cpp.py
index c320f03b2c..800d7fdd8c 100644
--- a/studio/backend/core/inference/llama_cpp.py
+++ b/studio/backend/core/inference/llama_cpp.py
@@ -1574,11 +1574,21 @@ class LlamaCppBackend:
             # ref: https://github.com/ggml-org/llama.cpp/blob/master/docs/speculative.md
             # ref: https://github.com/ggml-org/llama.cpp/pull/19164
             # ref: https://github.com/ggml-org/llama.cpp/pull/18471
+            # ``"default"`` -> let llama-server pick a sensible spec
+            # config via ``--spec-default``. Explicit type names are
+            # passed through with the manual draft tuning we've shipped
+            # historically so power users keep their overrides.
             _valid_spec_types = {"ngram-simple", "ngram-mod"}
-            if speculative_type and speculative_type in _valid_spec_types:
-                if not is_vision:  # spec decoding disabled for vision models
-                    cmd.extend(["--spec-type", speculative_type])
-                    if speculative_type == "ngram-mod":
+            normalized_spec = (
+                speculative_type.lower().strip() if speculative_type else None
+            )
+            if normalized_spec and normalized_spec != "off" and not is_vision:
+                if normalized_spec == "default":
+                    cmd.append("--spec-default")
+                    self._speculative_type = "default"
+                elif normalized_spec in _valid_spec_types:
+                    cmd.extend(["--spec-type", normalized_spec])
+                    if normalized_spec == "ngram-mod":
                         cmd.extend(
                             [
                                 "--spec-ngram-size-n",
@@ -1589,7 +1599,7 @@ class LlamaCppBackend:
                                 "64",
                             ]
                         )
-                    self._speculative_type = speculative_type
+                    self._speculative_type = normalized_spec
                 else:
                     self._speculative_type = None
             else:
@@ -1750,6 +1760,12 @@ class LlamaCppBackend:
             if gpu_indices is not None:
                 env["CUDA_VISIBLE_DEVICES"] = ",".join(str(i) for i in gpu_indices)
 
+            # Defensive kill: if a concurrent load slipped past Phase 1
+            # (because its `self._process` was None at the time) and
+            # already stored a Popen handle here, drop that orphan
+            # before we overwrite the reference. See issue #5161.
+            self._kill_process()
+
             self._stdout_lines = []
             self._process = subprocess.Popen(
                 cmd,
diff --git a/studio/frontend/src/features/chat/chat-settings-sheet.tsx b/studio/frontend/src/features/chat/chat-settings-sheet.tsx
index e4574dab74..fc5f097969 100644
--- a/studio/frontend/src/features/chat/chat-settings-sheet.tsx
+++ b/studio/frontend/src/features/chat/chat-settings-sheet.tsx
@@ -1037,7 +1037,7 @@ export function ChatSettingsPanel({
                           <SelectValue />
                         </SelectTrigger>
                         <SelectContent>
-                          <SelectItem value="ngram-mod">On</SelectItem>
+                          <SelectItem value="default">On</SelectItem>
                           <SelectItem value="off">Off</SelectItem>
                         </SelectContent>
                       </Select>
diff --git a/studio/frontend/src/features/chat/hooks/use-chat-model-runtime.ts b/studio/frontend/src/features/chat/hooks/use-chat-model-runtime.ts
index 1281592168..e90cab73fa 100644
--- a/studio/frontend/src/features/chat/hooks/use-chat-model-runtime.ts
+++ b/studio/frontend/src/features/chat/hooks/use-chat-model-runtime.ts
@@ -24,6 +24,19 @@ import type {
   InferenceParams,
 } from "../types/runtime";
 
+// The simplified Speculative Decoding control surfaces "default" (which
+// maps to llama.cpp's --spec-default) and "off". A backend status / load
+// response can still report the older manual modes (ngram-mod,
+// ngram-simple) when a model is loaded via the API or carried over from an
+// older Studio version. The Select would render an empty trigger for those
+// values, so coerce them to "default" -- llama.cpp's own --spec-default
+// picks an equivalent strategy and keeps the dropdown coherent.
+function normalizeSpeculativeType(v: string | null | undefined): string | null {
+  if (v == null) return null;
+  if (v === "default" || v === "off") return v;
+  return "default";
+}
+
 type SelectedModelInput = {
   id: string;
   isLora?: boolean;
@@ -279,7 +292,7 @@ export function useChatModelRuntime() {
         const ggufNativeContextLength = statusRes.is_gguf
           ? (statusRes.native_context_length ?? null)
           : null;
-        const currentSpecType = statusRes.speculative_type ?? null;
+        const currentSpecType = normalizeSpeculativeType(statusRes.speculative_type);
         useChatRuntimeStore.setState({
           supportsReasoning,
           reasoningAlwaysOn,
@@ -492,7 +505,7 @@ export function useChatModelRuntime() {
               }
             }
             const loadedKv = loadResponse.cache_type_kv ?? null;
-            const loadedSpec = loadResponse.speculative_type ?? null;
+            const loadedSpec = normalizeSpeculativeType(loadResponse.speculative_type);
             const nativeCtx = loadResponse.is_gguf
               ? (loadResponse.context_length ?? 131072)
               : null;
diff --git a/studio/frontend/src/features/chat/stores/chat-runtime-store.ts b/studio/frontend/src/features/chat/stores/chat-runtime-store.ts
index 2a1249aea0..ce69d8f6dc 100644
--- a/studio/frontend/src/features/chat/stores/chat-runtime-store.ts
+++ b/studio/frontend/src/features/chat/stores/chat-runtime-store.ts
@@ -270,7 +270,7 @@ export const useChatRuntimeStore = create<ChatRuntimeStore>((set) => ({
   toolCallTimeout: loadInt(TOOL_CALL_TIMEOUT_KEY, 5),
   kvCacheDtype: null,
   loadedKvCacheDtype: null,
-  speculativeType: "ngram-mod",
+  speculativeType: "default",
   loadedSpeculativeType: null,
   customContextLength: null,
   defaultChatTemplate: null,
@@ -365,7 +365,7 @@ export const useChatRuntimeStore = create<ChatRuntimeStore>((set) => ({
       toolStatus: null,
       kvCacheDtype: null,
       loadedKvCacheDtype: null,
-      speculativeType: "ngram-mod",
+      speculativeType: "default",
       loadedSpeculativeType: null,
       customContextLength: null,
       defaultChatTemplate: null,